Bulletin of the American Physical Society
68th Annual Gaseous Electronics Conference/9th International Conference on Reactive Plasmas/33rd Symposium on Plasma Processing
Volume 60, Number 9
Monday–Friday, October 12–16, 2015; Honolulu, Hawaii
Session KW1: Plasma Gas Conversion |
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Chair: Osamu Sakai, University of Shiga Prefecture Room: 301 B |
Wednesday, October 14, 2015 1:30PM - 2:00PM |
KW1.00001: Plasmolysis for efficient CO2-to-fuel conversion Invited Speaker: Gerard van Rooij The strong non-equilibrium conditions provided by the plasma phase offer the opportunity to beat traditional thermal process energy efficiencies via preferential excitation of molecular vibrational modes. It is therefore a promising option for creating artificial solar fuels from CO$_{2}$ as raw material using (intermittently available) sustainable energy surpluses, which can easily be deployed within the present infrastructure for conventional fossil fuels. In this presentation, a common microwave reactor approach is evaluated experimentally with Rayleigh scattering and Fourier transform infrared spectroscopy to assess gas temperatures and conversion degrees, respectively. The results are interpreted on basis of estimates of the plasma dynamics obtained with electron energy distribution functions calculated with a Boltzmann solver. It indicates that the intrinsic electron energies are higher than is favourable for preferential vibrational excitation due to dissociative excitation, which causes thermodynamic equilibrium chemistry still to dominate the initial experiments. Novel reactor approaches are proposed to tailor the plasma dynamics to achieve the non-equilibrium in which vibrational excitation is dominant.\\[4pt] In collaboration with Dirk van den Bekerom, Niek den Harder, Teofil Minea, Dutch Institute For Fundamental Energy Research, Eindhoven, Netherlands; Gield Berden, Institute for Molecules and Materials, FELIX facility, Radboud University, Nijmegen, Netherlands; Richard Engeln, Applied Physics, Plasma en Materials Processing, Eindhoven University of Technology; and Waldo Bongers, Martijn Graswinckel, Erwin Zoethout, Richard van de Sanden, Dutch Institute For Fundamental Energy Research, Eindhoven, Netherlands. [Preview Abstract] |
Wednesday, October 14, 2015 2:00PM - 2:15PM |
KW1.00002: Student Award Finalist: Transient Analysis of Pulsed Dry Methane Reforming in DBD-Catalyst Hybrid Reaction Keishiro Tamura, Seigo Kameshima, Yutaro Ishibashi, Ryo Mizukami, Takumi Yamazaki, Tomohiro Nozaki Pulsed dry methane reforming in DBD-catalyst hybrid reaction was investigated. Optical emission spectroscopy was also employed for the better understanding of reaction mechanism for enhanced CH4 and CO2 conversion as well as carbon removal reaction. Strong emission from C2 high pressure Swan system was uniquely observed when the Boudouard reaction dominates the surface reaction: C2 molecules were selectively produced via vibrationally excited CO which is originated from the adsorbed carbon on the catalysts. Time dependent change in gas composition and optical emission profiles of CO {\AA}ngstr\"om and C2 high pressure Swan systems were correlated in a systematic and consistent manner, leading to the deep insight into the CH4 and CO2 activation mechanisms over solid catalysts. Moreover, individual contribution of radical injection and heat generated by DBD were investigated. The result clearly showed that the CH4 and CO2 conversion rates were increased essentially by the radical injection, not the thermal effect of DBD. [Preview Abstract] |
Wednesday, October 14, 2015 2:15PM - 2:30PM |
KW1.00003: NH3 reforming by DBD using a H2 permeable membrane Yukio Hayakawa, Shinji Kambara, Tomonori Miura Ammonia is a hydrogen storage material that may solve several problems related to hydrogen transportation and storage in the hydrogen society. Catalytic thermal decomposition is a promising technique for producing hydrogen from ammonia. This study investigated atmospheric plasma decomposition as a new hydrogen production device. Therefore, it also observed that molecular ammonia was rapidly decomposed by electron energy in the plasma and was converted into molecular hydrogen. The hydrogen production was increased by the ammonia concentration, but hydrogen conversion was dramatically decreased to 13.9 {\%}, so unreacted ammonia was existed. In order to improve these problems, we developed a new high voltage electrode which was equipped with a hydrogen permeable membrane. At the result, this device could make high purity hydrogen at room temperature and unreacted ammonia was removed. [Preview Abstract] |
Wednesday, October 14, 2015 2:30PM - 2:45PM |
KW1.00004: Preliminary Characterization of a Coaxial DBD Plasma-Catalytic Converter for Methane Partial Oxidation Sylvain Coulombe, Pablo Diaz Gomez Maqueo, Mathew Evans, Florent Sainct, Jeff Bergthorson This contribution discusses the development and characteristics of a coaxial dielectric barrier discharge (DBD) using a methane-oxygen mixture at atmospheric conditions of temperature and pressure. A sinusoidal voltage waveform of 12 kVp-p at 20 kHz produces discharges in a 1.15 mm gap. Power is estimated using a Lissajous figure method while optical emission spectroscopy (OES) is used to estimate the rotational and vibrational temperatures of the gas. Obtained OES spectra are similar, differing mainly on the intensity of their CH and OH bands, tending towards a more intense OH band as oxygen availability increased. CH bands show the strongest emission intensities of which, CH(C-X) seems to be the most intense of all, followed by CH(A-X) and lastly by CH(B-X). The spectra of CH(A-X) and CH(C-X) were uploaded into a simulation software to estimate the plasma temperatures. For the CH(A-X) bands, a simulation with a Trot $=$ 600 K and a Tvib $=$ 6000 K matched the experimental spectra. In the case of the CH(C-X) band, a Trot $=$ 800 K and a Tvib $=$ 4000 K were determined. The vibrational temperatures are especially high, a result which is particularly important for the development of a plasma-catalysis reactor. [Preview Abstract] |
Wednesday, October 14, 2015 2:45PM - 3:00PM |
KW1.00005: Methane reforming in a temperature-controlled DBD reactor Dmitry Levko, Laxminarayan Raja Methane and carbon dioxide are among the main products of human activity. Therefore, they are considered among greenhouse gases, which may cause the global warming. On the other hand, methane is widely used in everyday life as an energy source and in industry for the synthesis of different chemicals. In order to utilize greenhouse gases or to generate chemicals from methane, one needs first to dissociate it. Then, this gas converts into desired products such as methanol, gasoline, syn-gas etc. Nowadays, there are several methods for CH4 conversion. Steam reforming, partial oxidation, thermal and non-thermal plasmas are among them. During the last decades, the use of non-thermal plasma for methane reforming attracts more and more attention. This is caused by the possibility to control the process of methane conversion as well as the gas component content at the reactor outlet. In addition, the use of non-thermal plasma facilitates the control of reactor start up. The goal of the present work is the deep understanding of the plasma chemical processes accompanying the methane-air conversion in a temperature-controlled DBD reactor. To do this, we have developed the kinetic mechanism of CH4/N2/O2 conversion for the gas temperature range 300-800 K and applied it to the global model. [Preview Abstract] |
Wednesday, October 14, 2015 3:00PM - 3:15PM |
KW1.00006: Investigation of atmospheric pressure streamer discharges for methane reforming M.V. Pachuilo, F. Stefani, L.A. Rosocha, L.L. Raja Hydrogen has several valuable uses in transportation: it can lower the coefficient of variation under lean burn conditions in internal combustion engines, and it is essential for the operation of fuel cells. Currently hydrogen can only be produced efficiently by reducing fossil fuels in large facilities. However, on-board production is desirable to reduce the infrastructure associated with storing and distributing hydrogen. Plasma dry reforming processes are viable candidates for onboard production. Our current work investigates the fundamental behavior of a single streamer discharge in methane. The electron temperature, and active species generation are determined through time resolved spectroscopy. This work will hopefully accelerate the development of non-thermal plasma based devices that include: dielectric barrier discharges, pulsed corona discharges, and other atmospheric-pressure plasma devices. [Preview Abstract] |
Wednesday, October 14, 2015 3:15PM - 3:30PM |
KW1.00007: Dependence of MnOx Catalyst Position on Toluene Decomposition using Nanosecond Pulsed Discharge Plasma Junkai Han, Akihiko Ogasawara, Jinlong Wang, Douyan Wang, Takao Namihira, Mitsuru Sasaki, Hidenori Akiyama, Pengyi Zhang Plasma catalysis, which combines advantages of high selectivity due to the catalysis and with fast ignition and response due to plasma technique, appears to be a promising technology to simultaneously resolve both efficiency and workability issues. In practice, a catalyst can be combined with NTP in two ways: by introducing the catalyst in the discharge zone (in-plasma catalytic reactor) or by placing the catalyst after the discharge zone (post-plasma catalytic reactor). This work aims to clarify combined effects by coupling MnOx catalyst with ns pulsed discharge system for decomposition of 100 ppm toluene utilizing three methods: plasma alone, in-plasma catalytic and post-plasma catalytic methods, in atmospheric pressure at room temperature. As the results, toluene removal ratio reached 100{\%} at approximately 50 J/L under the in-plasma catalytic and post-plasma catalytic methods, while it was 70{\%} under the plasma alone method. The concentrations of O3, HCOOH, and CO under the plasma alone method were higher compared with the in-plasma catalytic or post-plasma catalytic methods. CO2 selectivity under the post-plasma catalytic method was the highest of these three methods when toluene removal ratio exceeded 80{\%}. [Preview Abstract] |
Wednesday, October 14, 2015 3:30PM - 3:45PM |
KW1.00008: Development of High-speed and Environmentally Friendly Photoresist Removal Process using Pulsed Microwave Plasma in Water Vapor Tatsuo Ishijima, Takuya Kitano, Takuya Ito, Hiroaki Suzuki, Yasunori Tanaka, Yoshihiko Uesugi, Takashi Nishiyama, Hideo Horibe A novel photoresist removing technique using a pulsed microwave excited plasma produced in vaporized water bubble (MWBP) has remarkable properties such as environmentally-friendly and low temperature process. This photoresist removal method has been studied to apply a practical semiconductor manufacturing process. On the other hand, the minimal-fabrication system (minimal-fab) without using a clean room has been proposed and developed in order to adapt a high-variety low-volume semiconductor manufacturing process. Recently MOS device production has been succeeded using the minimal-fab. It is expected to evaluate the proposed MWBP ashing technology ability and clarify the possibility for a practical semiconductor manufacturing process to be incorporated in the minimal-fab. In order to apply MWBP for the minimal-fab, reduction of the input microwave power is necessary because the size of the minimal-fab is a compact and is highly standardized to maximize the convenience of the fabrication system utilization. In this study, we have investigated MWBP production methods to reduce the MWBP production power. We found that the decrease in the MWBP production power can be achieved by introducing a new bubble-control-structure to keep the bubble around the microwave antenna. [Preview Abstract] |
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